1. Field of the Invention
The present invention relates to an endoscope provided with a plurality of image pickup units and capable of simultaneously observing a plurality of observation fields of view, and an endoscope system provided with the endoscope.
2. Description of the Related Art
Recently, an endoscope system has been widely used, in medical and industrial fields for example, which is configured with: an endoscope configured having an image pickup portion at a distal end part, having such a bending portion that a predetermined area near a distal end is configured to be bendable and that is bendingly operated by a proximal side operation, and having an insertion portion formed in an elongated tube shape as a whole, an image processing control apparatus configured to control the endoscope and the like and process image data acquired by the endoscope, an image display apparatus configured to receive the image data acquired by the endoscope and processed by the image processing control apparatus to display an image, and the like.
A medical endoscope used in the medical field is configured so that it is possible to insert the elongated insertion portion into a body cavity to be a subject, observe an organ in the body cavity and, when necessary, perform various kinds of treatments using a treatment instrument inserted in a treatment instrument insertion channel provided in the endoscope. Further, an industrial endoscope used in the industrial field is configured so that it is possible to, by inserting the elongated insertion portion into an inside of an object, for example, a jet engine or plant piping, perform observation and inspection of a state inside the object, for example, observation of scratches, corrosion and the like.
In a conventional endoscope in a form of this kind, it is difficult to, for example, at a time of inserting the insertion portion of the endoscope into a body cavity to be a subject, more specifically, into a large bowel or the like, grasp which direction the distal end part of the endoscope inserted in the body cavity faces, only by a front-view image pickup optical system of an image pickup portion disposed at a distal end face of the endoscope and configured to secure a forward field of view, and this causes the work of inserting the insertion portion of the endoscope to be difficult.
Therefore, various kinds of configurations have been disclosed and have been put to practical use, such as a configuration in which, by providing a side-view type second image pickup portion in addition to an ordinary front-view image pickup portion, at a distal end portion of an endoscope, forward and lateral fields of view can be simultaneously secured (Japanese Patent Application Laid-Open Publication No. H9-313435 and the like), and a configuration in which a front-view or oblique-view type second image pickup portion is disposed in a vicinity of a joint between a bending portion and a flexible tube (hose), in addition to, for example, an ordinary front-view image pickup portion at a distal end portion of an endoscope (Japanese Patent Application Laid-Open Publication No. 2013-141487 and the like).
By devising a configuration as described above, an advantage is obtained that it becomes easy to grasp a facing direction of a distal end part of an endoscope being inserted and used in a body cavity or the like and it becomes easy to perform an insertion operation.